1. Field of the Invention
The invention relates to an automatic bowling pinsetter and, more particularly, to a cam and roller-based pit cushion follower assembly located between a pit cushion and a support arm of a pit cushion assembly of the pinsetter.
2. Discussion of the Related Art
Automatic pinsetters are widely used in bowling alleys to sweep downed pins from bowling lanes during and between frames and to set upright pins in place. Referring to FIG. 1, a pinsetter 20 is illustrated that is Model A-2 pinsetter manufactured by Brunswick Corporation. Pinsetter 20 includes as its major component a rake assembly 22 that sweeps pins from the lane L and into a pit area P located behind the lane, a vertically reciprocating deck (not shown) that sets the pins, and a pit cushion assembly 24 that acts as a backstop for bowling balls. The rake assembly 22 includes a rake sweep board 23 that is driven by a gearbox 26 and a rake lift cam 28, but is biased by a spring 29 to its downward or clockwise rotated position illustrated in phantom lines. Each side of the rake assembly 22 is also coupled to the pit cushion assembly 24 by a lower vertically adjustable link 30, an adjustable upper rake sweep link 32, and a pivoting triangular plate 34. Specifically, each vertical adjustable link 30 is attached to a pit cushion support assembly 44 at its lower end and to a pivoting triangular plate 34 at its upper end. Each upper sweep link 32 extends from the corresponding triangular plate 34 to a “V” lever 36 on a rake lift shaft 38 at the top of the pinsetter 20. The forward end of the left-hand pit cushion link (not shown) is attached to an adjustable link of a rake trip mechanism or “shot gun link” that lowers the rake sweep board 23 to the bowling lane L. Two kickbacks (not shown), one on each side of the bowling lane L, support and serve as mounts for the pinsetter 20. Mounting plates 40 are bolted to the top of the kickbacks.
The pit cushion assembly 24 is suspended across a pit area P behind the lane L to stop the motion of a bowling ball B after the ball passes through the bowling pins and falls into the pit area P. Pit cushion assembly 24 comprises a pit cushion 42 that extends across the lane and two support assemblies 44, one located at each end of the pit cushion, that suspend the pit cushion 42 above the pit area P. The pit cushion 42 comprises a steel plate 50 protected by pads 48 so as not to mark or damage bowling balls. A bottom end of the plate 50 is inclined forwardly relative to the remainder of the plate and is positioned just above the floor of the pit area A when the pit cushion assembly 24 is in its initial or deactivated position shown in solid lines in FIG. 1. A pit curtain 52 extends upwardly from the pit cushion 42 to hide objects behind the pit cushion 42 from view. A vertical mounting arm 48 is mounted on each end of the pit cushion 42 for connection to an associated support assembly 44.
Referring to FIGS. 1–3, each pit cushion support assembly 44 is attached to front and rear support brackets 60 and 62 mounted on the mounting plate 40. The upper end of a support arm 64 is pivotally mounted to each front bracket 60. An airplane type shock absorber 66 is pivotally attached to an intermediate portion of each support arm 64 at one end and to the rear kickback pit cushion-mounting bracket 62 at its opposite end. The shock absorber 66 relieves the sudden rearward motion of the pit cushion upon ball impact.
Referring to FIGS. 2 and 3, the vertical mounting arm 48 on each end of the pit cushion 42 is mounted on the associated support arm 64 by a pair of upper support arms 67 and a lower follower link assembly 68 which, in combination with pivoting movement of the support arm 64, permit the pit cushion 42 to swing upwardly and rearwardly upon ball impact so that a bowling ball B (FIG. 1) can pass under the pit cushion 42 to enter a ball elevator (not shown). They also permit the pit cushion 42 to lower at the end of the operational pinsetter cycle. The upper support arms 67 are pivotally mounted to common pivot points 70, 72 on the upper end of the vertical mounting arm 46 and an intermediate portion of the support arm 64, respectively.
The follower link assembly 68 of each support assembly 44 includes a pair of inclined follower links 74, each of which has an aperture 76 in its lower front end and an elongated slot 78 in its upper rear end. The lower end of the vertical support arm 64 contains a pressed bushing 80 in an aperture 84 thereof that acts as a pivot for the pit cushion 42. Inserted into bushing 80 is a steel spacer 82. Spacer 82 exceeds the length of the pressed bushing 80. Each steel spacer 82 acts as a pivot point for the lower end of the associated follower link 74. Specifically, the spacer 82 receives a ½ inch bolt 86 that pivotally attaches the follower link 74 to the bottom aperture 84 in the mounting arm 46. A uniball 88 is also attached to the bolt 86 for connection to the adjustable vertical link 30. The slot 78 in the upper end of each follower link 74 slidably receives a bushing assembly 90 which is mounted in a bottom aperture 92 in the support arm 64 by a ½ inch bolt 94. Coordinated pivoting of the follower links 74 about the bolts 94 and sliding movement of the bushing assemblies 90 along the slots 78 accommodates swinging movement of the pit cushion 42 relative to the support arms 64. The extent of relative movement of the pit cushion 42 away from the support arms 64 at the end of a return stroke occurring at the end of the pinsetter operational cycle is limited by the bottoming out of the bushing assemblies 90 in the slots 78.
In operation, the impact of a bowling ball B against the pit cushion 42 causes the pit cushion 42 to rotate clockwise and thus push the vertical links 30 upward. This upward movement rotates the triangular plates 34 clockwise, pushing the upper link 32 forward to unlatch the rake trip mechanism or shotgun link and lower the rake sweep board 23 to the bowling lane L. As the rake assembly 22 lowers the sweep board 23, the pit cushion link 32 rotates the triangular plates 34 clockwise and, through the vertical links 30, raises the pit cushion 42 to allow the bowling ball B to pass under the pit cushion 42 to the ball elevator (not shown). During the return stroke of the rake sweep board 23, the pit cushion 42 rotates counterclockwise and pulls the vertical links 30 downward, rotating the triangular plates 34 counterclockwise and moving the pit cushion 42 downward. The pit cushion 42 again is in position to await delivery of the next bowling ball. It can thus be seen that the rake sweep board 23 and pit cushion 42 operate together. When the rake sweep board 23 is down, the pit cushion 42 is up. When the rake sweep board 23 is up, the pit cushion 42 is down.
The follower link assembly 68 is viewed by pinsetter mechanics as an area with a high rate of mechanical failure and maintenance. Due to the severity and repetition of the bowling ball striking the pit cushion, the integrity of follower link assembly 68 has been known to deteriorate at an undesirable rate. The follower link assembly parts are used to control the position of the pit cushion prior to bowling ball impact, making the follower link assembly components susceptible to the severity of bowling ball impact. The pivot point of the pivot links 74 eventually degrades at the point of connection with the steel spacers 82 due to the severity of bowling ball impact and lack of adequate lubrication.
In addition, the urethane pivot rollers of the pivot links harden over time and resist pivoting of the follower link assembly and pit cushion. The follower link assembly part deterioration results in continued restricted pit cushion rotation, which in turn results in reduction of vertical link and triangular plate upward rotation upon bowling ball impact and making more difficult to unlatch the rake trip mechanism to begin the pinsetter operational cycle. As parts of the follower link assembly continue to deteriorate, component rotation continues to be seriously impeded, thus resulting in the need for the follower link assembly replacement to restore the rake trip mechanism performance to satisfactory operable condition.
In addition, the follower links 74 control the forward positioning of the lower end of the pit cushion 42. Due to the pit cushion position, bowling balls are susceptible to getting pinned between the pit cushion and ball lift rod assembly that could result in bowling ball damage and the failure to return the bowling ball back to the bowler.
The need has therefore arisen to provide a pit cushion follower that is simpler, less prone to wear, is less sensitive to part wear, and provides less restriction to pit cushion motion than link-based pit cushion followers.